果蔬气调库快速降氧时间的影响因素

摘要

为了使果蔬尽早进入气调状态,达到提高贮藏品质的目的,作者对影响气调库快速降氧时间的因素进行了研究.以西安某苹果气调库为研究对象,采用k-ε紊流模型建立了气调库内气体流动、传热与传质的三维数学求解模型,并通过编写UDF程序获得苹果呼吸强度和冷风机送风口O2、CO2质量分数随库内气体组分体积分数变化实时数据.通过改变制氮机工作参数和果蔬品种对该气调库的充氮降氧过程进行数值模拟,获得库内O2体积分数随时间变化的规律,并与实验数据呈现较好的一致性.结果表明:不同的氮气纯度对应着相应的最快降氧区间.作者研究对象选择体积分数为96％的氮气所需降氧时间最短,呼吸强度差别较大的果蔬降氧时间有明显差异.%Inorder to get the concentration of O2 and CO2 into the specified values as soon as possible,to improve the storage quality,this paper studied on the affecting factors of rapid oxygen reduction process in the CA room.This paper takes a CA room for apples in Xian as research object,by means of K-ε model establishing the three dimensional physical and mathematical models for gas flow,heat and mass transfer inside the CA storage.This paper solves the problems of the apples' changing respiration rate and the changing mass fractions of the velocity-inlet boundary by writing a UDF program.By numerical calculation we obtain the curves of O2 concentration varied with time in the CA storage,at the same time comparing the simulated results to the experimental data of the relative reference.The results show that the different nitrogen purity corresponds to the fastest oxygen-consumed interval.When the volume fraction of nitrogen is 96％,the time of rapid oxygen reduction process is the least.The respiration rate of fruits vary greatly which can significantly affect the time of the rapid oxygen reduction process.